German Application No. DE 43 38 342, not published prior to the date of filing of the present application, describes a method and a device for generating a simulated signal relating to the temperature of the exhaust gas, of the exhaust-gas probe, or of the catalytic converter. The known method determines a steady-state exhaust gas temperature with the aid of a characteristic curve. The time variation of the exhaust gas temperature upstream of the catalytic converter is simulated with the aid of a first filter, starting from the steady-state exhaust gas temperature. The temperature of the catalytic converter can further be determined with the aid of a second filter.
Furthermore, it is described in German Patent Application No. DE 44 24 811, likewise not published prior to the date of filing of the present application, when simulating the time variation of the exhaust gas temperature, starting from the steady-state exhaust gas temperature, to undertake a division into a fast and a slow component. The two components are further processed separately and subsequently superimposed again. Provision is made, furthermore, for using a correction factor to take account of cooling of the exhaust gases, which is a function of driving speed.
It is the object of the present invention to generate a signal which reproduces as accurately as possible a temperature in the exhaust system of an internal combustion engine.